Base station for switching between uplink periods and downlink periods in a time division manner

ABSTRACT

A base station that switches between uplink periods and downlink periods in a time division manner and performs communication, the base station includes a memory; processor circuitry coupled to the memory, wherein the processor circuitry is configured to: notify of allocation information indicating a combination of resources for time division duplex (TDD) uplink (UL) or downlink (DL) configuration at a predetermined interval; and generate control information indicating cancelation of transmission of a downlink signal, wherein the canceled transmission is configured to be performed by using one of the resources designated by the allocation information, and wherein the processor circuitry is further configured to transmit the generated control information.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application17/151,042 filed on Jan. 15, 2021, which is a divisional application ofU.S. Application 16/184,159, filed Nov. 8, 2018, which is a continuationapplication of International Application PCT/JP2016/064193 filed on May12, 2016, and designated the U.S., the entire contents of each areincorporated herein by reference.

FIELD

The present disclosure relates to a base station and a terminal.

BACKGROUND

5G (fifth generation mobile communication) has been examined as acommunication standard of the next generation. In the 5G, support ofmany use cases roughly classified into eMBB (Enhanced Mobile BroadBand),Massive MTC (Machine Type Communications), and URLLC (Ultra-Reliable LowLatency Communication) is assumed. The 5G aims at improvement offrequency use efficiency while efficiently supporting ultralow delaycommunication data and normal data simultaneously in the same interface.For example, the eMBB aims at setting a delay of a user plane in anuplink channel and a downlink channel to 4 milliseconds. The URLLC aimsat setting a delay of a user plane in an uplink channel and downlinkchannel to 0.5 millisecond.

In TDD-LTE (Time Division Duplex-Long Term Evolution), seven types ofcombinations (UL/DL configurations) of a subframe used for an uplinksignal and a subframe used for a downlink signal are defined. A basestation and a terminal perform communication based on a UL/DLconfiguration designated by the base station. In recent years, atechnique for switching a UL/DL configuration at 10 milliseconds at theshortest in order to cope with sudden fluctuation in communicationtraffic involved in a reduction in a cell size has been introduced.Related arts are disclosed in, for example, Japanese NationalPublication of International Patent Application No. 2014-522135,International Publication Pamphlet No. WO2013/069218, and 3GPPRP-160167.

Incidentally, the communication traffic between the base station and theterminal often deviates to one of the uplink signal or the downlinksignal. Therefore, communication is performed between the base stationand the terminal using a UL/DL configuration deviating to one of theuplink signal or the downlink signal.

Consequently, a large volume of data can be efficiently transmitted.However, if the UL/DL configuration deviates to one of the uplink signaland the downlink signal, when ultralow delay data occurs, transmissionis put off to a period of a subframe used for transmission of theultralow delay data. For example, when ultralow delay data occurs in theterminal, if a UL/DL configuration deviating to the downlink signal isused between the base station and the terminal, a waiting time to asubframe allocated to the uplink signal increases. Therefore, it isdifficult to satisfy a delay requested to transmission of the ultralowdelay data.

It is also conceivable to satisfy the delay requested to thetransmission of the ultralow delay data by using a UL/DL configurationin which the uplink signal and the downlink signal are alternatelytransmitted. However, in this case, transmission efficiency concerning alarge volume of data is deteriorated. In consideration of the situation,it is desirable that a delay requested to transmission of ultralow delaydata is satisfied while maintaining transmission efficiency of a largevolume of data.

SUMMARY

According to an aspect of the embodiments, a base station that switchesbetween uplink periods and downlink periods in a time division mannerand performs communication, the base station includes a memory;processor circuitry coupled to the memory, wherein the processorcircuitry is configured to: notify of allocation information indicatinga combination of resources for time division duplex (TDD) uplink (UL) ordownlink (DL) configuration at a predetermined interval; and generatecontrol information indicating cancelation of transmission of a downlinksignal, wherein the canceled transmission is configured to be performedby using one of the resources designated by the allocation information,and wherein the processor circuitry is further configured to transmitthe generated control information.

The object and advantages of the disclosure will be realized andattained by means of the elements and combinations particularly pointedout in the claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the disclosure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an example of a wireless communication system;

FIG. 2 illustrates an example of the structure of a frame;

FIG. 3 illustrates an example of an allocation table;

FIG. 4 illustrates an example of a combination of subframes included inone frame;

FIG. 5 is a block diagram illustrating an example of a base station;

FIG. 6 is a diagram for explaining an example of transmission timings ofan L-SR and ultralow delay data;

FIG. 7 is a diagram for explaining another example of the transmissiontimings of the L-SR and the ultralow delay data;

FIG. 8 is a block diagram illustrating an example of a terminal;

FIG. 9 is a flowchart illustrating an example of the operation of thebase station;

FIG. 10 is a flowchart illustrating an example of the operation of theterminal;

FIG. 11 is a sequence chart illustrating an example of the operation ofthe wireless communication system;

FIG. 12 illustrates an example of hardware of the base station; and

FIG. 13 illustrates an example of hardware of the terminal.

DESCRIPTION OF EMBODIMENTS

An embodiment of a base station, a terminal, a wireless communicationsystem, and a communication method disclosed by this application isexplained in detail below with reference to the drawing. Note that theembodiment explained below does not limit the disclosed technique.

Embodiment [Wireless Communication System 10]

FIG. 1 illustrates an example of a wireless communication system 10. Thewireless communication system 10 includes a base station 20 and aplurality of terminals 30-1 to 30-n. Note that, in the followingexplanation, when the plurality of terminals 30-1 to 30-n arecollectively referred to without being distinguished from one another,the plurality of terminals 30-1 to 30-n are simply described asterminals 30. In this embodiment, the base station 20 and the respectiveterminals 30 switch, in a time division manner, uplink signalstransmitted from the respective terminals 30 to the base station 20 anddownlink signals transmitted from the base station 20 to the respectiveterminals 30 and perform communication. The base station 20 and therespective terminals 30 perform communication based on, for example, aTDD-LTE (Time Division Duplex-Long Term Evolution) scheme.

The base station 20 and each terminals 30 perform transmission andreception of data not having a very high request concerning a delay buthaving a relatively large data amount (hereinafter described as largevolume data) and transmission and reception of data having a highrequest concerning a delay but having a relatively small data amount(hereinafter described as ultralow delay data). The large volume data isdata of a video, a file, and the like. The ultralow delay data iscontrol signals and data transmitted and received in automatic drive ofan automobile, remote surgery, and the like. Data other than theultralow delay data such as the large volume data is an example of thefirst data. The ultralow delay data is an example of the second data.

In this embodiment, transmission and reception of data is performedusing, for example, a frame having structure illustrated in FIG. 2between the base station 20 and the respective terminals 30. FIG. 2illustrates an example of the structure of the frame. For example, asillustrated in FIG. 2 , a plurality of subframes 40 are included in oneframe. Note that, in this embodiment, for example, as illustrated inFIG. 2 , continuous six subframes 40 are included in one frame. However,the number of subframes included in one frame may be five or less or maybe seven or more.

In each subframe 40, for example, as illustrated in FIG. 2 , a region 41to a region 45 are disposed in order from the head. The respectiveregions 41 to 45 are configured by a plurality of resource blocksspecified by combinations of frequencies and times. The region 41 is aregion where a control signal in a downlink direction, a referencesignal used for demodulation of and the control signal in the downlinkdirection, and the like are disposed. The region 42 is a region wheredata in the downlink direction, a reference signal used for demodulationof the data in the downlink direction, and the like are disposed. Thereference signals disposed in the region 41 and the region 42 are used,in the terminal 30, for measurement of the quality of a channel betweenthe terminal 30 and the base station 20 as well.

The region 43 is a guard period . The region 44 is a region where datain an uplink direction, a reference signal used for demodulation of thedata in the uplink direction, and the like are disposed. The region 45is a region where a control signal in the uplink direction, a referencesignal used for demodulation of the control signal in the uplinkdirection, and the like are disposed. In the following explanation, asignal disposed in the region 41 is described as DL_CTL, a signaldisposed in the region 42 is described as DL data, the region 43 isdescribed as GP, a signal disposed in the region 44 is described as ULdata, and a signal disposed in the region 45 is described as UL_CTL.

In the example illustrated in FIG. 2 , signals in the downlink directionare disposed in the region 41 and the region 42 and signals in theuplink direction are disposed in the region 44 and the region 45. Forexample, as illustrated in FIG. 2 , in each subframe 40, when the lengthof a region where a signal in the downlink direction is disposed isrepresented as m and the length of a region where a signal in the uplinkdirection is disposed is represented as n, a ratio of an uplink signaland a downlink signal in each subframe 40 is represented by acombination of m and n. The region where the signal in the downlinkdirection is disposed is an example of the downlink section. The lengthm of the region where the signal in the downlink direction is disposedis an example of the information indicating the length of the downlinkperiod. The region where the signal in the uplink direction is disposedis an example of the uplink period. The length n of the region where thesignal in the uplink direction is disposed is an example of theinformation indicating the length of the uplink period.

In this embodiment, several kinds of ratios of uplink signals anddownlink signals in each subframe 40 are decided in advance. FIG. 3illustrates an example of an allocation table 50. In this embodiment,for example, as illustrated in the allocation table 50 in FIG. 3 , fivekinds of ratios of uplink signals and downlink signals in each subframe40 are decided in advance. Note that combinations decided in advance asratios of uplink signals and downlink signals in each subframe 40 may befour kinds or less or may be six kinds or more.

For example, in the allocation table 50 illustrated in FIG. 3 , when acombination number is “0”, a ratio of a downlink signal and an uplinksignal in the subframe 40 is 9:1. In the subframe 40 in which the ratioof the downlink signal and the uplink signal is 9:1, for example, theregion 45 where the UL_CTL is disposed is provided in a region where theuplink signal is disposed. However, the region 44 where the UL data isdisposed is not provided.

For example, when the combination number is “1” to “3”, the region 42where the DL data is disposed and the region 44 where the UL data isdisposed are provided in the subframe 40. For example, when thecombination number is “4”, a ratio of a downlink signal and an uplinksignal in the subframe 40 is 1:9. In the subframe 40 in which the ratioof the downlink signal and the uplink signal is 1:9, the region 41 wherethe DL_CTL is disposed is provided in a region where the downlink signalis disposed. However, the region 42 where the DL data is disposed is notprovided. In the allocation table in FIG. 3 , when the combinationnumber is any one of “0” to “4”, the region 41 where the DL_CTL isdisposed, the region 43 of the GP, and the region 45 where the UL_CTL isdisposed are provided in each subframe 40. Note that a combination ofsubframes not including a region of an uplink signal at all, acombination of subframes not including a region of a downlink signal atall, or a combination of subframes (Muting subframes) not including aregion of an uplink signal and a region of a downlink signal may beincluded combinations that can be allocated.

Note that, in this embodiment, in each subframe 40, the region 41 to theregion 45 are disposed in order from the head of the subframe 40.However, the order of the region 41 to the region 45 is not limited tothe example illustrated in FIG. 2 . For example, in each subframe 40,the region 41 and the region 42 may be disposed in the opposite orderand the region 44 and the region 45 may be disposed in the oppositeorder. For example, in each subframe 40, the region 43 to the region 45may be disposed further on the head side in the subframe 40 than theregion 41 and the region 42.

In this embodiment, the base station 20 creates allocation informationfor designating, in frame units, a combination of ratios of uplinksignals and downlink signals in each subframe 40 and notifies thecreated allocation information to each terminal 30. The allocationinformation is notified to each terminal 30 using a channel such as aBCH (Broadcast CHannel) or a PDCCH (Physical Downlink Control CHannel).For example, when the allocation information created by the base station20 is {0, 0, 0, 0, 4, 0}, the base station 20 and each terminal 30communicate using, for example, a frame configured by six subframes 40illustrated in FIG. 4 . FIG. 4 illustrates a combination of subframesincluded in one frame. In FIG. 4 , subframes 40-1 to 40-6 are disposedin order from the head of the frame.

When the allocation information is {0, 0, 0, 0, 4, 0}, for example, asillustrated in FIG. 4 , the region 42 where the DL data is disposed isprovided in the subframes 40-1 to 40-4 and the subframe 40-6. However,the region 44 where the UL data is disposed is not provided. On theother hand, in the subframe 40-5, the region 44 where the UL data isdisposed is provided. However, the region 42 where the DL data isdisposed is not provided.

In this way, the base station 20 decides the several kinds ofcombinations of ratios of uplink signals and downlink signals in eachsubframe 40 in advance and notifies, to each terminal 30, allocationinformation designating a combination used in communication.Consequently, flexibility of a combination of rations of uplink signalsand downlink signals in each subframe 40 is improved. A data amount innotifying a combination of ratios of uplink signals and downlink signalsin each subframe 40 to each terminal 30 can be reduced.

In this embodiment, in each subframe 40, the region 41 where the DL_CTLis disposed and the region 45 where the UL_CTL is disposed are provided.Consequently, the base station 20 and each terminal 30 can transmit acontrol signal to the counter apparatuses at least in each subframe 40.Therefore, the base station 20 and each terminal 30 can reduce a waitingtime from time when data to be transmitted occurs until transmission ofthe data is started.

In this embodiment, when ultralow delay data occurs in the terminal 30,the terminal 30 notifies a transmission request for the ultralow delaydata to the base station 20 using the region 45 used for a controlsignal in the uplink direction in the nearest subframe 40. In thefollowing explanation, the transmission request for the ultralow delaydata is described as L-SR (Scheduling Request for Low latencycommunications). Note that a plurality of resources used fortransmission of the L-SR are disposed for each terminal 30 in the region45 used for the control signal in the uplink direction.

When receiving the L-SR from the terminal 30, the base station 20detects the occurrence of the ultralow delay data. The base station 20allocates a resource for the ultralow delay data to the region 44 wherethe UL data is disposed in the subframe 40 two subframes after thesubframe 40 in which the L-SR is transmitted. In the followingexplanation, the subframe 40 in which the L-SR is transmitted isdescribed as first subframe 40 and the subframe 40 used for thetransmission of the ultralow delay data is described as second subframe40.

The base station 20 disposes a switching instruction for the terminal 30at the transmission source of the L-SR in the region 41 where the DL_CTLis disposed in the second subframe 40. An instruction for switching aresource in the second subframe 40 to a resource for the ultralow delaydata, information concerning the resource switched for the ultralowdelay data, and the like are included in the switching instruction. Notethat an instruction itself to perform the switching of the resource doesnot have to be explicitly transmitted. The instruction itself to performthe switching may be implicitly notified by notifying resourceinformation for the ultralow delay data to the terminal 30 or notifyingpermission concerning the transmission of the ultralow delay data usinga predetermined resource. By differentiating, in advance, a transmissionformat or a transmission resource of resource allocation information ofthe ultralow delay data from a transmission format or a transmissionresource for data, which is not the ultralow delay data, the basestation 20 may inform the terminal 30 whether the instruction is aninstruction related to the ultralow delay data (that is, an instructionmore preferential than a combination of ratios of uplink signals anddownlink signals notified in advance) or an instruction based on thecombination of ratios of uplink signals and downlink signals notified inadvance.

After transmitting the L-SR, the terminal 30 monitors the region 41 ineach subframe 40. When a switching instruction addressed to the terminal30 is disposed in the region 41, the terminal 30 transmits, according tothe switching instruction, the ultralow delay data to the base station20 using the resource allocated for the ultralow delay data in theregion 44 where the UL data is disposed. Consequently, even when a ratioof a downlink signal is set higher than a ratio of an uplink signal ineach subframe 40 in order to increase a throughput of the large volumedata, the terminal 30 can quickly start transmission of the occurredultralow delay data. Consequently, the wireless communication system 10in this embodiment can satisfy a delay requested to the transmission ofthe ultralow delay data while maintaining transmission efficiency of thelarge volume data.

[Base Station 20]

FIG. 5 is a block diagram illustrating an example of the base station20. The base station 20 includes, for example, as illustrated in FIG. 5, a QoS (Quality of Service) control unit 21, a resource allocating unit22, a control-signal generating unit 23, and an allocation-informationcontrol unit 24. The base station 20 includes, for example, asillustrated in FIG. 5 , a scheduler 25, an uplink-signal-basebandprocessing unit 26, a radio unit 27, an antenna 28, and a tableretaining unit 29. Note that, in FIG. 5 , among functional blocksincluded in the base station 20, blocks concerning transmission of acontrol signal in the downlink direction and blocks concerning receptionof a control signal and data in the uplink direction are illustrated.The control-signal generating unit 23 is an example of the notifyingunit. The scheduler 25 is an example of the creating unit.

The radio unit 27 executes, on a control signal output from thecontrol-signal generating unit 23, processing such as conversion from adigital signal into an analog signal and upconvert and generates atransmission signal. The radio unit 27 transmits the generatedtransmission signal via the antenna 28. The radio unit 27 executes, on asignal received from the terminal 30 via the antenna 28, processing suchas downconvert and conversion from an analog signal into a digitalsignal and generates a reception signal. The radio unit 27 outputs thegenerated reception signal to the uplink-signal-baseband processing unit26.

The QoS control unit 21 receives, from an MME (Mobility ManagementEntity) or the like in a core network 11, a delay condition,communication speed, and the like requested to services provided to theterminal 30. Services for treating ultralow delay data such as automaticdrive of an automobile and remote surgery, services for treating largevolume data such as a video and a file, and the like are included in theservices provided to the terminal 30. The QoS control unit 21determines, based on the delay condition, the communication speed, andthe like, whether resources used for the L-SR are prepared for theterminal 30 to which the service is provided. When determining that theresources used for the L-SR are prepared, the QoS control unit 21instructs the resource allocating unit 22 to allocate the resources usedfor the L-SR.

The resource allocating unit 22 allocates the resources used for theL-SR, according to the instruction from the QoS control unit 21, to theterminal 30. The resource allocating unit 22 outputs transmissionrequest information indicating the allocation of the resources used forthe L-SR to the control-signal generating unit 23. The resourceallocating unit 22 allocates, for example, for each of the subframes 40,the resource of the L-SR to the region 41 of the DL_CTL in the subframe40. Note that resources used for a transmission request of data otherthan the ultralow delay data such as large volume data are allocated tothe region 41 of the DL_CTL in the subframe 40 at a time interval longerthan a time interval of the L-SR.

In this embodiment, the resource allocating unit 22 allocates theresources used for the L-SR and the resources used for the transmissionrequest for the data other than the ultralow delay data to separateresources. However, the disclosed technique is not limited to this. Theresource allocating unit 22 may allocate the resources used for the L-SRand the resources used for the transmission request for the data otherthan the ultralow delay data to the same resource for each of theterminals 30. In this case, the L-SR and the transmission request forthe data other than the ultralow delay data are distinguished by contentof data included in the transmission request. For example, the L-SR andthe transmission request for the data other than the ultralow delay dataare distinguished according to a value of a specific flag included inthe transmission request.

The table retaining unit 29 retains, for example, the allocation table50 illustrated in FIG. 3 . The allocation-information control unit 24determines a ratio of an uplink signal and a downlink signal in eachsubframe 40 in one frame according to a state of communication trafficbetween the base station 20 and each terminal 30 (for example, a typeand an amount of data transmitted and received between the base station20 and each terminal 30). The allocation-information control unit 24refers to the allocation table 50 in the table retaining unit 29 andselects a combination number corresponding to the determined ratio. Theallocation-information control unit 24 outputs the selected combinationnumber to the control-signal generating unit 23 and the scheduler 25 asallocation information in frame units.

The uplink-signal-baseband processing unit 26 performs processing suchas demodulation and decoding on the reception signal output from theradio unit 27 and extracts a control signal and reception data. Theuplink-signal-baseband processing unit 26 outputs the control signal tothe scheduler 25 and outputs the reception data to the core network 11.

The scheduler 25 determines, based on the control signal output from theuplink-signal-baseband processing unit 26, whether the L-SR is received.When the L-SR is received, the scheduler 25 detects occurrence ofultralow delay data. The scheduler 25 specifies, as a second subframe 40used for transmission of the ultralow delay data, for example, thesubframe 40 two subframes after the first subframe 40 to which the L-SRis transmitted. Note that the scheduler 25 may specify, as the secondsubframe 40, the subframe 40 three or more subframes after the firstsubframe 40 according to a processing ability or the like of theterminal 30. However, to reduce a transmission delay of the ultralowdelay data, it is desirable to specify, as the second subframe 40, thesubframe 40 close to the first subframe 40.

The scheduler 25 determines whether the specified second subframe 40 isa changeable subframe 40. In this embodiment, a change is prohibitedconcerning the subframe 40 including data, transmission timing of whichis important, such as a synchronization signal and important systeminformation. When the second subframe 40 is the changeable subframe 40,the scheduler 25 refers to the allocation information output from theallocation-information control unit 24 and the allocation table 50 inthe table retaining unit 29. The scheduler 25 determines whether theregion 44 of the UL data is included in the second subframe 40. When theregion 44 of the UL data is included in the second subframe 40, thescheduler 25 determines whether the region 44 of the UL data included inthe second subframe 40 has a size sufficient for disposing the ultralowdelay data. In this embodiment, a data amount of the ultralow delay datatransmitted at one time is determined in advance. Note that the dataamount of the ultralow delay data transmitted at one time may be anydata amount. However, in that case, information indicating the dataamount of the ultralow delay data is included in the L-SR.

When the region 44 of the UL data included in the second subframe 40 hasthe size sufficient for disposing the ultralow delay data, the scheduler25 creates a switching instruction including an instruction forswitching a resource in the second subframe 40 to a resource for theultralow delay data. Information indicating a resource allocated totransmission of the ultralow delay data in the region 44 of the UL dataincluded in the second subframe 40 is included in the switchinginstruction. Besides information indicating a combination of a frequencyand time allocated to transmission of data, information for designatingtransmission power, an MCS (Modulation and Coding Scheme), and the likeis included in the information indicating the resource allocated to thetransmission of the ultralow delay data. The switching instruction istransmitted to the terminal 30 at the transmission source of the L-SRusing a channel in the downlink direction such as the PDCCH.

When a resource in the region 44 of the UL data before being switched toa resource for transmission of the ultralow delay data is allocated totransmission of the UL data of the terminal 30, the scheduler 25 createsa suspension instruction for instructing the terminal 30 to suspend thetransmission of the UL data. The suspension instruction is transmittedto, using a channel in the downlink direction such as the PDCCH, theterminal 30 to which the resource in the region 44 of the UL data beforebeing switched to the resource for the transmission of the ultralowdelay data is allocated. The terminal 30 that receives the suspensioninstruction suspends transmission of data scheduled to be transmittedusing the resource in the region 44 of the UL data before being switchedto the resource for the transmission of the ultralow delay data.

When the region 44 of the UL data is not included in the second subframe40 or when the region 44 of the UL data of the second subframe 40 doesnot have the size enough for disposing the ultralow delay data, thescheduler 25 performs determination explained below. That is, when atleast a part of the region 42 of the DL data of the second subframe 40is switched to the region 44 of the UL data, the scheduler 25 determineswhether the region 44 having the size enough for disposing the ultralowdelay data is secured. When the region 44 having the size enough fordisposing the ultralow delay data is secured by the switching, thescheduler 25 creates a switching instruction including an instructionfor switching at least a part of the region 42 of the DL data to aresource for the ultralow delay data.

When at least a part of the region 42 of the DL data is switched to theresource for the ultralow delay data, the scheduler 25 creates a changenotification indicating that the region 42 of the DL data is changed tothe resource for the ultralow delay data. The change notification isnotified to each terminal 30 belonging to the base station 20 using achannel in the downlink direction such as the BCH. Consequently, theterminal 30 that measures the quality of the channel between theterminal 30 and the base station 20 based on the reference signalincluded in the region 42 of the DL data before being changed to theresource for the ultralow delay data can recognize that the content ofthe region 42 of the DL data is changed. Consequently, the terminal 30can exclude, from a measurement target of the quality of the channel,the subframe 40 changed to the resource for the ultralow delay data.Therefore, the terminal 30 can stop deterioration in measurementaccuracy of the quality of the channel due to the change of the region42 of the DL data to the resource for the ultralow delay data.

When the transmission request information indicating the allocation ofthe resources used for the L-SR is output from the resource allocatingunit 22, the control-signal generating unit 23 creates a control signalincluding the transmission request information. When the allocationinformation is output from the allocation-information control unit 24,the control-signal generating unit 23 creates a control signal includingthe allocation information. When the switching instruction, thesuspension instruction, or the change notification is output from thescheduler 25, the control-signal generating unit 23 creates a controlsignal including these kinds of information. The control-signalgenerating unit 23 performs processing such as encoding and modulationon the created control signal. The control-signal generating unit 23disposes a signal after the processing in the region 41 in the subframe40 and outputs the signal to the antenna 28. The subframe 40 in whichthe control signal in the downlink direction is disposed is transmittedfrom the antenna 28 by the radio unit 27.

FIGS. 6 and 7 are diagrams for explaining an example of transmissiontimings of the L-SR and the ultralow delay data. In FIGS. 6 and 7 , itis assumed that the subframes 40 in each frame are disposed, forexample, as illustrated in FIG. 4 . In FIGS. 6 and 7 , it is assumedthat a change is not prohibited in all the subframes 40.

For example, as illustrated in FIG. 6 , when the L-SR is transmittedfrom the terminal 30 in the region 45 where the UL_CTL is disposed inthe subframe 40-1, the scheduler 25 specifies, as the second subframe40, the subframe 40-3 two subframes after the subframe 40-1. In theexample illustrated in FIG. 4 , the region 44 of the UL data is notincluded in the subframe 40-3. Therefore, the scheduler 25 switches apart of the region 42 of the DL data in the subframe 40-3 to the region44 of the UL data including the resource for the ultralow delay data.The scheduler 25 creates a switching instruction including aninstruction for switching a part of the region 42 of the DL data to theresource for the ultralow delay data and a change notificationindicating that the region 42 of the DL data is changed to the resourcefor the ultralow delay data. The created switching instruction isdisposed in the region 41 of the DL_CTL in the subframe 40-3 andtransmitted to the terminal 30 at the transmission source of the L-SR.The created change notification is disposed in the region 41 of theCL_CTL in the subframe 40-3 and notified to each terminal 30.

The terminal 30 that receives the switching instruction transmits theultralow delay data using the resource in the subframe 40-3 designatedby the switching instruction. In this embodiment, the length of eachsubframe 40 is, for example, 100 to 150 microseconds. In the exampleillustrated in FIG. 6 , the ultralow delay data is transmitted to thebase station 20 within 450 microseconds after the occurrence of theultralow delay data is detected in the terminal 30. Therefore, thewireless communication system 10 in this embodiment can starttransmission of the ultralow delay data within 0.5 millisecond from theoccurrence of the ultralow delay data.

For example, as illustrated in FIG. 7 , when the L-SR is transmittedfrom the terminal 30 in the region 45 of the UL_CTL in the subframe40-3, the scheduler 25 specifies, as the second subframe 40, thesubframe 40-5 two subframes after the subframe 40-3. In the exampleillustrated in FIG. 4 , the region 44 of the UL data is included in thesubframe 40-5. However, the resource for the ultralow delay data withrespect to the L-SR is not included in the region 44 of the UL data.Therefore, the scheduler 25 switches a part of resources in the region44 of the UL data in the subframe 40-5 to a resource 44-1 for theultralow delay data. Consequently, the resource 44-1 for the ultralowdelay data and a resource 44-2 for data other than the ultralow delaydata are included in the region 44 of the UL data in the subframe 40-5.Note that, when a part of the region 44 of the UL data is switched tothe resource 44-1 for the ultralow delay data, it is desirable to switcha region on the head side in the region 44 to the resource 44-1 for theultralow delay data. Consequently, it is possible to more quickly startthe transmission of the ultralow delay data.

Note that, when a resource before being switched to the resource 44-1for the ultralow delay data is already allocated to the terminal 30 asthe resource for the data other than the ultralow delay data, thescheduler 25 creates a suspension instruction to the terminal 30. Thecreated suspension instruction is disposed in the region 41 of theDL_CTL in the subframe 40-5 and transmitted to the terminal 30 to whichthe resource being switched to the resource 44-1 for the ultralow delaydata is allocated.

[Terminal 30]

FIG. 8 is a block diagram illustrating an example of the terminal 30.The terminal 30 includes, for example, as illustrated in FIG. 8 , ahigh-order-layer processing unit 31, a control-signal processing unit32, a communication control unit 33, a downlink-signal-basebandprocessing unit 34, a transmission-request transmitting unit 35, anuplink-signal-baseband processing unit 36, a radio unit 37, an antenna38, and a table retaining unit 39. The downlink-signal-basebandprocessing unit 34 and the uplink-signal-baseband processing unit 36 areexamples of the communication unit. The control-signal processing unit32 is an example of the receiving unit. The high-order-layer processingunit 31 is an example of the detecting unit. The transmission-requesttransmitting unit 35 is an example of the transmitting unit. Thedownlink-signal-baseband processing unit 34 is an example of themeasuring unit.

The radio unit 37 executes, on signals output from thetransmission-request transmitting unit 35 and the uplink-signal-basebandprocessing unit 36, processing such as conversion from a digital signalinto an analog signal and upconvert and generates a transmission signal.The radio unit 37 transmits the generated transmission signal to thebase station 20 via the antenna 38. The radio unit 37 performs, on asignal received from the base station 20 via the antenna 38, processingsuch as downconvert and conversion from the analog signal into thedigital signal and outputs a signal after the processing to thedownlink-signal-baseband processing unit 34.

The downlink-signal-baseband processing unit 34 estimates a channelbased on the signal output from the radio unit 37, demodulates anddecodes the signal output from the radio unit 37 using the estimatedchannel, and generates a reception signal. The downlink-signal-basebandprocessing unit 34 extracts reception data and a control signal from thereception signal, outputs the reception data to the high-order-layerprocessing unit 31, and outputs the control signal to the control-signalprocessing unit 32. Transmission request information, allocationinformation, a switching instruction, a suspension instruction, a changenotification, and the like are included in the control signal.

The downlink-signal-baseband processing unit 34 measures the quality ofthe channel between the base station 20 and the terminal 30 based on thesignal of each subframe 40 output from the radio unit 37. For example,the downlink-signal-baseband processing unit 34 measures the quality ofthe channel between the base station 20 and the terminal 30 usingreference signals disposed in the region 41 and the region 42 in eachsubframe 40. The downlink-signal-baseband processing unit 34 creates aCQI (Channel Quality Indicator) indicating the measured quality of thechannel and outputs the created CQI to the uplink-signal-basebandprocessing unit 36.

Note that, when the change notification indicating that the region 42 ofthe DL data is changed to the resource for the ultralow delay data isincluded in the control signal, the downlink-signal-baseband processingunit 34 excludes, from the measurement target of the quality of thechannel, the subframe 40 changed to the resource for the ultralow delaydata. Consequently, the downlink-signal-baseband processing unit 34 canstop deterioration in measurement accuracy of the quality of the channeldue to the change of the region 42 of the DL data to the resource forthe ultralow delay data.

When transmission request information addressed to the terminal 30 isincluded in the control signal output from the downlink-signal-basebandprocessing unit 34, the control-signal processing unit 32 outputs thetransmission request information to the transmission-requesttransmitting unit 35. When allocation information, a switchinginstruction, and a suspension instruction addressed to the terminal 30are included in the control signal output from thedownlink-signal-baseband processing unit 34, the control-signalprocessing unit 32 outputs the allocation information, the switchinginstruction, and the suspension instruction to theuplink-signal-baseband processing unit 36.

The high-order-layer processing unit 31 executes peculiar processing ofthe terminal 30. The high-order-layer processing unit 31 executesprocessing for treating ultralow delay data of, for example, automaticdrive of an automobile and remote surgery, processing for treating largevolume data such as a video and a file, and the like. When data to betransmitted to the base station 20 occurs, the high-order-layerprocessing unit 31 outputs the data to the communication control unit33. When reception data is output from the downlink-signal-basebandprocessing unit 34, the high-order-layer processing unit 31 executesprocessing based on the reception data. For example, in the automaticdrive of the automobile, when detecting occurrence of heavy braking,abrupt steering, or the like based on outputs from various sensorsprovided in the automobile, the high-order-layer processing unit 31detects occurrence of ultralow delay data to be transmitted to the basestation 20. The high-order-layer processing unit 31 outputs informationindicating a state of the automobile (for example, a position, speed,and a moving direction of the automobile) to the communication controlunit 33 as the ultralow delay data. The high-order-layer processing unit31 controls a brake, a steering wheel, and the like of the automobilebased on states of other automobiles included in the reception dataoutput from the downlink-signal-baseband processing unit 34.

When the ultralow delay data is output from the high-order-layerprocessing unit 31, the communication control unit 33 notifies theoccurrence of the ultralow delay data to the transmission-requesttransmitting unit 35 and outputs the ultralow delay data output from thehigh-order-layer processing unit 31 to the uplink-signal-basebandprocessing unit 36. When data other than the ultralow delay data such aslarge volume data is output from the high-order-layer processing unit31, the communication control unit 33 outputs the data to theuplink-signal-baseband processing unit 36.

When the occurrence of the ultralow delay data is notified from thecommunication control unit 33, the transmission-request transmittingunit 35 creates an L-SR. The transmission-request transmitting unit 35disposes the created L-SR in a resource designated by the transmissionrequest information output from the control-signal processing unit 32 inthe nearest subframe 40. The transmission-request transmitting unit 35outputs, to the radio unit 37, a signal in which the L-SR is disposed inthe resource designated by the transmission request information.Consequently, the L-SR is disposed in the resource designated by thetransmission request information and transmitted to the base station 20.

The table retaining unit 39 retains, for example, the allocation table50 illustrated in FIG. 3 . When allocation information is output fromthe control-signal processing unit 32, the uplink-signal-basebandprocessing unit 36 refers to the allocation table 50 in the tableretaining unit 39 and specifies a ratio of an uplink signal and adownlink signal in each subframe 40. When data other than the ultralowdelay data is output from the communication control unit 33, theuplink-signal-baseband processing unit 36 performs processing such asencoding and modulation on the data. The uplink-signal-basebandprocessing unit 36 disposes a signal after the processing in a resourceof an uplink signal allocated to the terminal 30 in each subframe 40.The uplink-signal-baseband processing unit 36 outputs, to the radio unit37, a signal in which the data other than the ultralow delay data isdisposed in the resource of the uplink signal allocated to the terminal30. Consequently, the data other than the ultralow delay data istransmitted to the base station 20 using the resource of the uplinksignal. When a CQI is output from the downlink-signal-basebandprocessing unit 34, the uplink-signal-baseband processing unit 36disposes information indicating the CQI in the region 45 of the UL_CTLand outputs the information to the radio unit 37. Consequently, theinformation indicating the CQI is transmitted to the base station 20using a resource of the UL_CTL.

When a switching instruction is output from the control-signalprocessing unit 32, the uplink-signal-baseband processing unit 36performs, according to an MCS included in the switching instruction,processing such as encoding and modulation of the ultralow delay dataoutput from the communication control unit 33. Theuplink-signal-baseband processing unit 36 adjusts, according to atransmission power value included in the switching instruction outputfrom the control-signal processing unit 32, transmission power of theultralow delay data on which the processing such as encoding andmodulation is performed. The uplink-signal-baseband processing unit 36disposes the ultralow delay data, the transmission power of which isadjusted, in a resource designated by the switching instruction. Theuplink-signal-baseband processing unit 36 outputs, to the radio unit 37,a signal in which the ultralow delay data is disposed in the resourcedesignated by the switching instruction. Consequently, the ultralowdelay data is transmitted to the base station 20 using the resourcedesignated by the switching instruction. When a suspension instructionis output from the control-signal processing unit 32, theuplink-signal-baseband processing unit 36 suspends transmission of datascheduled to be transmitted in the resource designated by the suspensioninstruction.

[Operation of the Base Station 20]

FIG. 9 is a flowchart illustrating an example of the operation of thebase station 20. The base station 20 executes operation illustrated inthe flowchart of FIG. 9 for each of the subframes 40. In this flowchart,the operation of the base station 20 during reception of ultralow delaydata is illustrated.

First, the scheduler 25 determines whether an L-SR is included in theregion 45 where the UL_CTL in the subframe 40 is disposed (S100). Whenan L-SR is not included in the region 45 (S100: No), the base station 20ends the operation illustrated in this flowchart.

On the other hand, when an L-SR is included in the region 45 where theUL_CTL is disposed (S100: Yes), the scheduler 25 specifies, as thesecond subframe 40, for example, the subframe 40 two subframes after thesubframe 40 to which the L-SR is transmitted. The scheduler 25determines whether the second subframe 40 is a changeable subframe 40(S101). When the second subframe 40 is not the changeable subframe 40(S101: No), the base station 20 ends the operation illustrated in thisflowchart. Note that, when the subframe 40 two subframes after thesubframe 40 to which the L-SR is transmitted is not the changeablesubframe 40, the scheduler 25 may specify, as the second subframe 40,the subframe 40 three or more subframes after the subframe 40 to whichthe L-SR is transmitted.

When the second subframe 40 is the changeable subframe 40 (S101: Yes),the scheduler 25 extracts L-SRs from the region 45 in the subframe 40.The scheduler 25 selects one unselect L-SR out of the extracted L-SRs(S102). Note that a plurality of L-SRs transmitted from each terminal 30are sometimes included in the region 45 in the subframe 40.

Subsequently, the scheduler 25 determines whether a space sufficient fordisposing the ultralow delay data is present in a resource in the region44 where UL data is disposed in the second subframe 40 (S103). Notethat, when a resource for other ultralow delay data is already allocatedto the region 44, the scheduler 25 determines whether a space sufficientfor disposing the ultralow delay data is present in a resource of theregion 44 not allocated for the ultralow delay data. When the sufficientspace is present in the resource in the region 44 (S103: Yes), thescheduler 25 determines whether an unallocated resource sufficient fortransmission of the ultralow delay data is present in the resource inthe region 44 (S104).

When an unallocated resource sufficient for the transmission of theultralow delay data is present in the region 44 (S104: Yes), thescheduler 25 allocates a resource for the ultralow delay data to theterminal 30 at the transmission source of the L-SR selected in step S102in the region 44. The scheduler 25 creates a switching instructionincluding, for example, an instruction for switching the resource in thesecond subframe 40 to the resource for the ultralow delay data (S105)and executes processing illustrated in step S111.

On the other hand, when an unallocated resource sufficient for thetransmission of the ultralow delay data is absent in the region 44(S104: No), the scheduler 25 executes processing explained below. Thatis, the scheduler 25 allocates a resource in the region 44, which isalready allocated to transmission of the data other than the ultralowdelay data, to the resource for the ultralow delay data from theterminal 30 at the transmission source of the L-SR selected in stepS102. The scheduler 25 creates a switching instruction including, forexample, an instruction for switching the resource in the secondsubframe 40 to the resource for the ultralow delay data (S106). Thescheduler 25 creates a suspension instruction for instructing suspensionof the transmission of the data to the terminal 30 to which the resourcebeing switched to the resource for the ultralow delay data is allocated(S107) and executes the processing illustrated in S111.

On the other hand, when a space sufficient for disposing the ultralowdelay data is absent in the region 44 where the UL data is disposed inthe second subframe 40 (S103: No), the scheduler 25 executes processingexplained below. That is, the scheduler 25 determines whether asufficient space is secured if the resource in the region 42 of the DLdata is changed to a resource for the UL data (S108). When thesufficient space is not secured even if the resource in the region 42 ofthe DL data is changed to the resource for the UL data (S108: No), thescheduler 25 executes the processing illustrated in step S111. Notethat, when the sufficient space is not secured even if the resource inthe region 42 of the DL data is changed to the resource for the UL data,a resource for the ultralow delay data corresponding to the L-SRselected in step S102 is not secured. However, when the resource for theultralow delay data corresponding to the L-SR is not secured, theterminal 30 retransmits the L-SR. Therefore, the resource for theultralow delay data corresponding to the L-SR is secured before long.

On the other hand, when the sufficient space is secured if the resourcein the region 42 of the DL data is changed to the resource for the ULdata (S108: Yes), the scheduler 25 allocates at least a part ofresources in the region 42 of the DL data to the resource for theultralow delay data. The scheduler 25 creates a switching instructionincluding, for example, an instruction for switching the resource in thesecond subframe 40 to the resource for the ultralow delay data (S109).The scheduler 25 creates a change notification indicating that theresource in the region 42 of the DL data is changed to the resource forthe ultralow delay data (S110).

Subsequently, the scheduler 25 determines whether all L-SRs in theregion 45 of the UL_CTL of the subframe 40 have been selected (S111).When an unselected L-SR is present (S111: No), the scheduler 25 executesthe processing illustrated in step S102. On the other hand, when all theL-SRs have been selected (S111: Yes), the scheduler 25 transmits thecreated switching instruction, the created suspension instruction, andthe created change notification to the control-signal generating unit23.

The control-signal generating unit 23 creates a control signal includingthe switching instruction and the suspension instruction and transmitsthe created control signal to each terminal 30 via the radio unit 27using a channel such as the PDCCH (S112). The control-signal generatingunit 23 creates a control signal including the change notification andtransmits the created control signal to each terminal 30 via the radiounit 27 using a channel such as the BCH (S112). The base station 20 endsthe operation illustrated in this flowchart.

[Operation of the Terminal 30]

FIG. 10 is a flowchart illustrating an example of the operation of theterminal 30. In the flowchart illustrated in FIG. 10 , the operation ofthe terminal 30 in transmission of ultralow delay data is illustrated.

First, the high-order-layer processing unit 31 determines, based onsignals output from the sensors, whether ultralow delay data occurs(S200). When ultralow delay data does not occur (S200: No), thehigh-order-layer processing unit 31 executes processing illustrated inS200 again.

On the other hand, when ultralow delay data occurs (S200: Yes), thehigh-order-layer processing unit 31 outputs the ultralow delay data tothe communication control unit 33. The communication control unit 33notifies the occurrence of the ultralow delay data to thetransmission-request transmitting unit 35 and outputs the ultralow delaydata to the uplink-signal-baseband processing unit 36.

The transmission-request transmitting unit 35 creates an L-SR anddisposes the created L-SR in a resource designated by transmissionrequest information output from the control-signal processing unit 32 inthe nearest subframe 40. The transmission-request transmitting unit 35outputs, to the radio unit 37, a signal in which the L-SR is disposed inthe resource designated by the transmission request information.Consequently, the L-SR is disposed in the resource designated by thetransmission request information and transmitted to the base station 20(S201).

Subsequently, the control-signal processing unit 32 refers to a controlsignal output from the downlink-signal-baseband processing unit 34 anddetermines whether a switching instruction is received (S202). When aswitching instruction is received (S202: Yes), the control-signalprocessing unit 32 outputs the switching instruction to theuplink-signal-baseband processing unit 36. The uplink-signal-basebandprocessing unit 36 disposes the ultralow delay data output from thecommunication control unit 33 in a resource designated by the switchinginstruction output from the control-signal processing unit 32. Theuplink-signal-baseband processing unit 36 outputs, to the radio unit 37,a signal in which the ultralow delay data output from the communicationcontrol unit 33 is disposed in the resource designated by the switchinginstruction. Consequently, the ultralow delay data is transmitted to thebase station 20 using the resource designated by the switchinginstruction (S203). The high-order-layer processing unit 31 executesprocessing illustrated in step S200 again.

[Operation of the Wireless Communication System 10]

FIG. 11 is a sequence chart illustrating an example of the operation ofthe wireless communication system 10.

First, the terminal 30 transmits, according to, for example, power-on oroperation of a service start by a user, a service connection request forrequesting a service for treating ultralow delay data to the basestation 20 (S300). The base station 20 transfers the service connectionrequest received from the terminal 30 to the MME 110 in the core network11 (S301). The MME 110 determines, for example, based on subscriberinformation and billing information, propriety of provision of theservice for treating the ultralow delay data. When permitting theprovision of the service for treating the ultralow delay data, the MME110 transmits, to the base station 20, a service connection responseincluding information to the effect that the provision of the service ispermitted and information such as a delay condition requested to theservice (S302). The base station 20 transmits, to the terminal 30, theservice connection response including the information to the effect thatthe provision of the service for treating the ultralow delay data ispermitted and transmission request information for instructing resourcesused for transmission of the ultralow delay data (S303).

Subsequently, the base station 20 determines, based on communicationtraffic between the base station 20 and the terminal 30, for each of theframes, a ratio of an uplink signal and a downlink signal concerningeach subframe 40 included in the frame. The base station 20 notifiesallocation information indicating a combination of determined ratios toeach terminal 30 using a channel such as the BCH (S304). Concerning dataother than the ultralow delay data such as large volume data, the basestation 20 and the terminal 30 transmit and receive the data usingresources of the uplink signal and the downlink signal allocatedaccording to the allocation information (S305).

When detecting occurrence of ultralow delay data (S306), the terminal 30transmits an L-SR to the base station 20 using the resource instructedby the transmission request information received in step S303 (S307).When receiving the L-

SR from the terminal 30, the base station 20 detects the occurrence ofthe ultralow delay data in the terminal 30. If, for example, the secondsubframe 40 two subframes after the subframe 40 to which the L-SR istransmitted is a changeable subframe 40, the base station 20 switchesthe region 44 of the UL data in the second subframe 40 to the resourcefor the ultralow delay data (S308). The base station 20 transmits, tothe terminal 30, using a channel such as the PDCCH, a switchinginstruction for instructing switching of the region 44 of the UL data inthe second subframe 40 to the resource for the ultralow delay data(S309). Resource information for instructing resources used fortransmission of the ultralow delay data is included in the switchinginstruction. Information such as the subframe 40, a frequency, time, anMCS, and transmission power used for the transmission of the ultralowdelay data is included in the resource information.

When receiving the switching instruction, the terminal 30 performsprocessing such as encoding and modulation of the ultralow delay dataaccording to the MCS and a transmission power value included in theswitching instruction and adjusts transmission power of a signal afterthe processing. The terminal 30 disposes the ultralow delay data, thetransmission power of which is adjusted, in the resource designated bythe switching instruction and transmits the ultralow delay data to thebase station 20 (S310).

Hardware

FIG. 12 illustrates an example of hardware of the base station 20. Thebase station 20 includes, for example, as illustrated in FIG. 12 , awireless communication circuit 200, a memory 201, a processor 202, anetwork interface 203, and the antenna 28.

The wireless communication circuit 200 applies predetermined processingsuch as modulation to a signal output from the processor 202 andtransmits a transmission signal after the processing via the antenna 28.The wireless communication circuit 200 applies predetermined processingsuch as demodulation to a reception signal received via the antenna 28and outputs the reception signal to the processor 202. The wirelesscommunication circuit 200 realizes, for example, the function of theradio unit 27. The network interface 203 is an interface for connectingthe base station 20 to the core network 11 through wired connection.

Programs and the like for realizing the functions of the QoS controlunit 21, the resource allocating unit 22, the control-signal generatingunit 23, the allocation-information control unit 24, the scheduler 25,and the uplink-signal-baseband processing unit 26 are stored in thememory 201. Data and the like in the table retaining unit 29 are storedin the memory 201. The processor 202 reads out the programs from thememory 201 and executes the programs to thereby realize, for example,the functions of the QoS control unit 21, the resource allocating unit22, the control-signal generating unit 23, the allocation-informationcontrol unit 24, the scheduler 25, and the uplink-signal-basebandprocessing unit 26.

Note that not all of the programs in the memory 201 have to be stored inthe memory 201 from the beginning. For example, the programs may bestored in a portable recording medium such as a memory card insertedinto the base station 20. The base station 20 may acquire the programsof a portion used for processing from such a portable recording mediumand execute the programs. The base station 20 may acquire the programsfrom another computer, a server apparatus, or the like, in which theprograms are stored, via a wireless communication line, a public line,the Internet, a LAN, a WAN, or the like and execute the programs.

FIG. 13 illustrates an example of hardware of the terminal 30. Theterminal 30 includes, for example, as illustrated in FIG. 13 , awireless communication circuit 300, a memory 301, a processor 302, auser interface 303, and the antenna 38.

The wireless communication circuit 300 applies predetermined processingsuch as modulation to a signal output from the processor 302 andtransmits a transmission signal after the processing via the antenna 38.The wireless communication circuit 300 applies predetermined processingsuch as demodulation to a reception signal received via the antenna 38and outputs the reception signal to the processor 302. The wirelesscommunication circuit 300 realizes, for example, the function of theradio unit 37. The user interface 303 includes an input device thatreceives operation from the user of the terminal 30 and a display devicethat displays a processing result.

Programs and the like for realizing the functions of thehigh-order-layer processing unit 31, the control-signal processing unit32, the communication control unit 33, the downlink-signal-basebandprocessing unit 34, the transmission-request transmitting unit 35, andthe uplink-signal-baseband processing unit 36 are stored in the memory301. Data and the like in the table retaining unit 39 are stored in thememory 301. The processor 302 reads out programs from the memory 301 andexecutes the programs to realize the functions of the high-order-layerprocessing unit 31, the control-signal processing unit 32, thecommunication control unit 33, the downlink-signal-baseband processingunit 34, the transmission-request transmitting unit 35, and theuplink-signal-baseband processing unit 36.

Note that not all of the programs in the memory 301 have to be stored inthe memory 301 from the beginning. For example, the programs may bestored in a portable recording medium such as a memory card insertedinto the terminal 30. The terminal 30 may acquires the programs of aportion used for processing from such a portal recording medium andexecute the programs. The terminal 30 may acquire the programs fromanother computer, a server apparatus, or the like, in which the programsare stored, via a wireless communication line, a public line, theInternet, a LAN, a WAN, or the like and execute the programs.

Effects of the Embodiment

As explained above, the base station 20 in this embodiment is the basestation 20 that switches an uplink signal and a downlink signal in atime division manner between the base station 20 and the terminal 30.The base station 20 includes the control-signal generating unit 23 andthe scheduler 25. The control-signal generating unit 23 notifies, to theterminal 30, allocation information for designating, for communicationusing data other than the ultralow delay data such as large volume data,allocation of resources of the uplink signal and the downlink signal foreach of a continuous predetermined number of subframes 40. Whendetecting occurrence of ultralow delay data, the scheduler 25 creates aswitching instruction including an instruction for switching a part ofthe resources of the uplink signal and the downlink signal designated bythe allocation information to a resource for the ultralow delay data.The control-signal generating unit 23 notifies the switching instructioncreated by the scheduler 25 to the terminal 30. Consequently, the basestation 20 can satisfy a delay requested to transmission of the ultralowdelay data while maintaining transmission efficiency of large volumedata.

In this embodiment, an uplink period used for an uplink signal and adownlink period used for a downlink signal are included in each subframe40. Concerning each subframe 40, information indicating the lengths ofthe uplink period and the downlink period included in the subframe 40 isincluded in the allocation information. The scheduler 25 creates aswitching instruction for switching at least a part of resources in theuplink period or the downlink period indicated by the allocationinformation to a resource for the ultralow delay data in the subframe 40after the occurrence of the ultralow delay data is detected.Consequently, in each subframe 40, an L-SR for requesting transmissionof the ultralow delay data can be transmitted to the base station 20. Adelay from the occurrence of the ultralow delay data to the transmissionof the L-SR can be reduced to a delay equal to or shorter than a timelength of one subframe 40. Therefore, it is possible to quickly requestthe base station 20 to transmit the ultralow delay data.

In this embodiment, when receiving an L-SR from the terminal 30 in theuplink period included in any subframe 40, the scheduler 25 detects theoccurrence of the ultralow delay data. The scheduler 25 creates aswitching instruction for switching at least a part of resources in theuplink period into a resource for the ultralow delay data in the secondsubframe 40 after the first subframe 40 in which the L-SR is received.The control-signal generating unit 23 transmits the switchinginstruction to the terminal 30 at the transmission source of the L-SR.Consequently, the terminal 30 can quickly transmit the ultralow delaydata occurred in the terminal 30 to the base station 20.

In this embodiment, when the scheduler 25 creates the switchinginstruction for switching at least a part of the resources in the uplinkperiod to the resource for the ultralow delay data, the scheduler 25creates a suspension instruction for instructing transmission suspensionof the uplink signal when the part of the resources is already allocatedto an uplink signal of another terminal 30. The control-signalgenerating unit 23 notifies the suspension instruction created by thescheduler 25 to the other terminal 30 to which the resource before beingswitched to the resource for the ultralow delay data is allocated.Consequently, it is possible to avoid collision of the ultralow delaydata and data transmitted from the other terminal 30.

In this embodiment, when the resources in the uplink period are fewerthan resources for the ultralow delay data in the second subframe 40,the scheduler 25 creates a switching instruction for switching at leasta part of resources in the downlink period included in the secondsubframe 40 to a resource for the ultralow delay data. The scheduler 25creates a change notification for notifying that the resource in thedownlink period of the second subframe 40 is changed to the resource forthe ultralow delay data. The control-signal generating unit 23 transmitsthe switching instruction to the terminal 30 at the transmission sourceof the L-SR and notifies the change notification to the terminal 30.Consequently, each terminal 30 can exclude, from a measurement target ofthe quality of a channel, the subframe 40 changed to the resource forthe ultralow delay data and can stop deterioration in measurementaccuracy of the quality of the channel.

In this embodiment, the terminal 30 is the terminal 30 that switches anuplink signal and a downlink signal in a time division manner betweenthe terminal 30 and the base station 20 and performs communication. Theterminal 30 includes the control-signal processing unit 32, thedownlink-signal-baseband processing unit 34, and theuplink-signal-baseband processing unit 36. The downlink-signal-basebandprocessing unit 34 and the uplink-signal-baseband processing unit 36perform communication with the base station 20 based on the allocationinformation notified from the base station 20. The control-signalprocessing unit 32 receives, from the base station 20, a switchinginstruction including an instruction for switching a part of resourcesof an uplink signal or a downlink signal designated by the allocationinformation to a resource for the ultralow delay data. When thecontrol-signal processing unit 32 receives the switching instruction,the uplink-signal-baseband processing unit 36 performs transmission ofthe ultralow delay data using the resource after the switching accordingto the switching instruction. Consequently, the terminal 30 can satisfya delay requested to the transmission of the ultralow delay data whilemaintaining transmission efficiency of large volume data.

In this embodiment, the terminal 30 includes the high-order-layerprocessing unit 31 and the transmission-request transmitting unit 35.The high-order-layer processing unit 31 detects occurrence of ultralowdelay data. When the occurrence of the ultralow delay data is detectedby the high-order-layer processing unit 31, the transmission-requesttransmitting unit 35 transmits an L-SR to the base station 20 in theuplink period of the subframe 40 after the occurrence of the ultralowdelay data is detected. Consequently, the terminal 30 can quicklytransmit the ultralow delay data occurred in the terminal 30 to the basestation 20.

In this embodiment, when receiving the suspension instruction from thebase station 20, the uplink-signal-baseband processing unit 36 suspendstransmission of data other than the ultralow delay data in the uplinkperiod. Consequently, it is possible to avoid collision of datatransmitted from the terminal 30 and the ultralow delay data transmittedfrom another terminal 30.

In this embodiment, the downlink-signal-baseband processing unit 34measures, based on the allocation information, the quality of thechannel between the terminal 30 and the base station 20 based on areference signal transmitted in the downlink period of each subframe 40.When receiving the change notification from the base station 20, thedownlink-signal-baseband processing unit 34 excludes, from themeasurement target of the quality of the channel, the subframe 40 inwhich the resource in the downlink period is changed to the resource forthe ultralow delay data. Consequently, each terminal 30 can stopdeterioration in measurement accuracy of the quality of the channel.

Others

Note that the disclosed technique is not limited to the embodimentexplained above. Various modifications are possible within the range ofthe gist of the disclosed technique.

For example, in the embodiment explained above, the base station 20includes, in the switching instruction, the information concerning theresources such as the MCS used for the transmission of the ultralowdelay data and transmits the information to the terminal 30. However,the disclosed technique is not limited to this. For example, the basestation 20 may notify a part of the information concerning the resourcessuch as the MCS used for the transmission of the ultralow delay data toeach terminal 30 in advance and include, in the switching instruction,the remainder of the information concerning the resources used for thetransmission of the ultralow delay data and transmit the remainder ofthe information to the terminal 30.

For example, the control-signal generating unit 23 notifies, to eachterminal 30, transmission request information for designating resourcesused for transmitting the L-SR in each subframe 40 and designationinformation for designating at least a part of information forspecifying resources used for the transmission of the ultralow delaydata. When the L-SR is transmitted, the control-signal generating unit23 notifies, to the terminal 30 at the transmission source of the L-SR,the remainder of the information for specifying the resources used forthe transmission of the ultralow delay data.

The control-signal processing unit 32 of the terminal 30 receives thetransmission request information and the designation informationnotified from the base station 20. When the occurrence of the ultralowdelay data is detected by the high-order-layer processing unit 31, theuplink-signal-baseband processing unit 36 creates a first transmissionsignal including the ultralow delay data according to the designationinformation notified from the base station 20. When the occurrence ofthe ultralow delay data is detected by the high-order-layer processingunit 31, the transmission-request transmitting unit 35 transmits atransmission request to the base station 20 using a resource designatedby the transmission request information. The remainder of theinformation for specifying the resources used for the transmission ofthe ultralow delay data is included in the switching instruction. Whenreceiving the switching instruction from the base station 20, theuplink-signal-baseband processing unit 36 creates a second transmissionsignal from the first transmission signal according to informationincluded in the switching instruction and transmits the created secondtransmission signal to the base station 20.

For example, the control-signal generating unit 23 of the base station20 includes, in the transmission request information, for example,information concerning a MCS and a transmission power value as at leasta part of the information for specifying the resources used for thetransmission of the ultralow delay data. When the L-SR is transmitted,the control-signal generating unit 23 includes, in the switchinginstruction, information concerning a frequency and time as theremainder of the information for specifying the resources used for thetransmission of the ultralow delay data.

When the occurrence of the ultralow delay data is detected by thehigh-order-layer processing unit 31, the uplink-signal-basebandprocessing unit 36 of the terminal 30 executes processing such asencoding, modulation, and power adjustment on the ultralow delay dataaccording to the instruction information notified from the base station20 and creates the first transmission signal. When receiving theswitching instruction from the base station 20, theuplink-signal-baseband processing unit 36 disposes the firsttransmission signal in a resource block corresponding to the frequencyand the time included in the switching instruction according to theinformation included in the switching instruction to thereby create thesecond transmission signal. The second transmission signal created bythe uplink-signal-baseband processing unit 36 is subjected to processingsuch as upconvert by the radio unit 37 and transmitted to the basestation 20 as a transmission signal. Consequently, when detecting theoccurrence of the ultralow delay data, the terminal 30 can execute theprocessing such as encoding, modulation, and power adjustment of theultralow delay data in parallel to the transmission of the L-SR.Therefore, in the terminal 30, processing after the reception of theswitching instruction from the base station 20 is reduced in thetransmission of the ultralow delay data. Therefore, even if a processingability of the terminal 30 is not so high, the terminal 30 can transmitthe ultralow delay data using the resource designated by the switchinginstruction.

Note that any information among the information concerning the resourcesused for the transmission of the ultralow delay data may be included inthe information notified from the base station 20 to each terminal 30 asthe designation information. All the information concerning theresources used for the transmission of the ultralow delay data may beincluded in the information notified from the base station 20 to eachterminal 30 as the designation information. However, the quality of thechannel between the base station 20 and the terminal 30 fluctuates withtime according to radio wave environments of the base station 20 and theterminal 30. Therefore, concerning information concerning a frequencyand time for specifying a resource block among the informationconcerning the resources used for the transmission of the ultralow delaydata, it is desirable to designate information concerning a resourceblock with satisfactory quality at a point in time when the switchinginstruction is transmitted.

For example, the base station 20 may notify candidates of the resourcessuch as the MCS used for the transmission of the ultralow delay data toeach terminal 30 in advance and, when transmitting the switchinginstruction, designate resources used for the transmission of theultralow delay data among the candidates.

For example, the control-signal generating unit 23 of the base station20 notifies, to each terminal 30, transmission request information fordesignating a resource used to transmit the L-SR in each subframe 40 anddesignation information for designating candidates of a plurality ofresources used for the transmission of the ultralow delay data. When theL-SR is transmitted from the terminal 30, the control-signal generatingunit 23 notifies, to the terminal 30 at the transmission source of theL-SR, information for specifying resources used for the transmission ofthe ultralow delay data among the candidates.

The control-signal processing unit 32 of the terminal 30 receives thetransmission request information and the designation informationnotified from the base station 20. When the occurrence of the ultralowdelay data is detected by the high-order-layer processing unit 31, theuplink-signal-baseband processing unit 36 creates, according to thedesignation information notified from the base station 20, atransmission signal including the ultralow delay data for each of thecandidates of the resources used for the transmission of the ultralowdelay data. When the occurrence of the ultralow delay data is detectedby the high-order-layer processing unit 31, the transmission-requesttransmitting unit 35 transmits a transmission request to the basestation 20 using resources designated by the transmission requestinformation. Information for specifying the resources used for thetransmission of the ultralow delay data among the candidates of theresources used for the transmission of the ultralow delay data isincluded in the switching instruction. When receiving the switchinginstruction from the base station 20, the uplink-signal-basebandprocessing unit 36 transmits, to the base station 20, a transmissionsignal for using the resources specified by the information included inthe switching instruction.

Consequently, when detecting the occurrence of the ultralow delay data,the terminal 30 can start, in parallel to the transmission of the L-SR,creation of a transmission signal for each of the candidates of theresources used for the transmission of the ultralow delay data.Therefore, when receiving the switching instruction from the basestation 20, the terminal 30 can select, out of created transmissionsignals, a transmission signal for using the resources specified by theinformation included in the switching instruction and transmits thetransmission signal to the base station 20. Consequently, even if aprocessing ability of the terminal 30 is not so high, the terminal 30can transmit the ultralow delay data using the resources designated bythe switching instruction.

Note that, in the embodiment explained above, a transmission procedurein the case in which the ultralow delay data occurs in the terminal 30is explained. However, the disclosed technique is not limited to this.For example, the disclosed technique can also be applied when theultralow delay data occurs in the base station 20.

In the embodiment explained above, the processing blocks respectivelyincluded in the base station 20 and the terminal 30 are divided for therespective functions according to main processing contents in order tofacilitate understanding of the base station 20 and the terminal 30 inthe embodiment. Therefore, the disclosed technique is not limited by amethod of dividing the processing blocks and names of the processingblocks. The processing blocks included in the base station 20 and theterminal 30 in the embodiment explained above can be further subdividedinto a larger number of processing blocks according to processingcontent. A plurality of processing blocks can be integrated into oneprocessing block. The processing executed by the respective processingblock may be realized as processing by software or may be realized bydedicated hardware such as an ASIC (Application Specific IntegratedCircuit).

All examples and conditional language provided herein are intended forthe pedagogical purposes of aiding the reader in understanding thedisclosure and the concepts contributed by the inventor to further theart, and are not to be construed as limitations to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the disclosure. Although one or more embodiments of thepresent disclosure have been described in detail, it should beunderstood that the various changes, substitutions, and alterationscould be made hereto without departing from the spirit and scope of thedisclosure.

What is claimed is:
 1. A terminal comprising: a transmitter configuredto transmit an uplink signal; a receiver configured to: receiveinformation indicating allocation information used for communicationwith a base station from among a plurality of pieces of allocationinformation, each of the plurality of pieces of allocation informationindicating a combination of resources for time division duplex (TDD) ofuplink (UL) or downlink (DL) configuration at a predetermined interval,and receive control information indicating cancelation of transmissionof the uplink signal; and processor circuitry configured to control thetransmitter not to transmit the uplink signal via a first resource amongthe resources for the UL configuration when the receiver receivescontrol information indicating to cancel transmission of the uplinksignal, wherein the plurality of pieces of allocation informationinclude: first allocation information that does not include the ULconfiguration; and second allocation information that does not includethe DL configuration.
 2. The terminal according to claim 1, wherein thetransmitter configured to transmit a first allocation request for afirst uplink data or a second allocation request for a second uplinkdata, the second uplink data has a higher delay requirement than thefirst uplink data.
 3. The terminal according to claim 2, wherein thefirst allocation request of resource is allocated a first cycle, thesecond allocation request of resource is allocated a second cycle, thesecond cycle is shorter than the first cycle.
 4. The terminal accordingto claim 2, wherein the transmitter transmits the second allocationrequest when the second data is occurred.
 5. The terminal according toclaim 1, wherein the plurality of pieces of allocation informationincludes first allocation information, second allocation information,and third allocation information, the first allocation information doesnot include UL period at the predetermined interval, the secondallocation information does not include DL period at the predeterminedinterval, and the third allocation information does not include the ULperiod and the DL period at the predetermined interval.
 6. The terminalaccording to claim 1, wherein the receiver receives allocationinformation allocated for two or more predetermined intervals.
 7. Theterminal according to claim 6, wherein each of the two or morepredetermined intervals correspond to one of a predetermined number ofsubframes.
 8. The terminal according to claim 7, wherein the receiverreceives change information for changing an allocation ratio ofresources of uplink and downlink signals.